Conventional wheel covers are typically retained on motor vehicle wheels by spring clips engaging an outer flange of the wheel or some other convenient location on the wheel. Severe wheel impacts have been known to dislodge wheel covers so retained from the wheels and of course, this form of retainment allows the wheel covers to be easily stolen.
Another method of retaining the wheel covers on vehicle wheels is exemplified by the wheel trim retention system shown in U.S. Pat. No. 4,998,780 issued Mar. 12, 1991 to Eshler, et al. The system shown in this patent employs decorative plastic caps which pass through apertures in the wheel cover and threadably engage an exterior thread on the lug nuts which retain the vehicle wheel on the vehicle. The plastic caps include a retainer to hold them on the wheel cover. Although this arrangement retains the wheel cover on the vehicle wheel, it is undesirable in that it increases the number of parts required to mount the wheel and wheel cover. An additional source of increased assembly complexity resides in the fact that the 5 lug nuts must be tightened to a fairly high torque level, and the plastic caps would be tightened to a relatively low torque level, thus making the use of a single torque control installation device unfeasible. Further, additional assembly labor and time is required since both the lug nuts and the plastic lug nut caps must be installed in separate operations. A further disadvantage of the Eshler et al system is that in some cases, the decorative plastic caps may loosen from the lug nuts because of jarring and vibration, thereby resulting in rattling of the caps on the wheel cover, or even loss of the wheel cover from the wheel.
It would therefore be desirable to provide a system for positively retaining wheel covers on motor vehicle wheels which require only one threading and torquing operation per lug nut. It would also beneficial to reduce the number of parts handled by a vehicle assembler at the wheel and wheel cover mounting point on the assembly line. The present invention is directed to satisfying these and other objectives.